This by itself is highly unusual (I've never seen it during 20 years in and around the tech IPO business.)

But, just as important, news of the estimate cut was passed on only to a handful of big investor clients, not everyone else who was considering an investment in Facebook.

This is a huge problem, for one big reason:

Selective dissemination. Earnings forecasts are material information, especially when they are prepared by analysts who have had privileged access to company management. As lead underwriters on the IPO, these analysts would have had much better information about the company than anyone else. So the fact that these analysts suddenly all cut their earnings forecasts at the same time, during the roadshow, and then this information was not passed on to the broader public, is a huge problem.

Any investor considering an investment in Facebook would consider an estimate cut from the underwriters' analysts "material information."

What's more, it's likely that news of these estimate cuts dampened interest in the IPO among those who heard about them. (Reuters reported exactly this—that some institutions were "freaked out" by the estimate cuts, as anyone would have been.)

In other words, during the marketing of the Facebook IPO, investors who did not hear about these underwriter estimate cuts were placed at a meaningful and unfair information disadvantage. They did not know what a lot of other investors knew, and they suffered for it.

Selective dissemination of this sort could be a direct violation of securities laws. Irrespective of its legality, it is also grossly unfair. The SEC should investigate this immediately.

The first one is bad news for Morgan Stanley and the other lead underwriters on the deal.

The second is also bad news for Facebook.

According to Reuters, the underwriter analysts cut their estimates after Facebook issued an amended IPO prospectus in which the company mentioned, vaguely, that recent trends in which users were growing faster than revenue had continued into the second quarter.

To those experienced in reading financial statements, this language was unnerving, because its mere existence could have been taken to mean that Facebook's revenue in the second quarter wasn't coming in as strong as Facebook had hoped (why else would the language have suddenly been added at the 11th hour?)

To those who aren't experienced at reading filings, however, the real meaning of this language could easily have been missed. Facebook's users have been growing faster than revenue for a while, so why would it be news that this was continuing?

In response to the amendment, meanwhile, all three lead underwriter analysts suddenly cut their estimates.

WATCH: How Low Will FB Stock Go?

Now, regardless of why the analysts cut their estimates (and this will be important), estimate cuts of any sort are material information, so if this news was given to some institutional clients, it also obviously should have been given to everyone.

That's the first problem.

The second potential question and problem is whether Facebook told the underwriters to cut their estimates—either by directly telling them to, or, more likely, by "suggesting" that the analysts might want to revisit their estimates in light of the new disclosures in the prospectus.

If there was any communication at all between Facebook and its underwriters regarding the analysts' estimates, Facebook will likely be on the hook for this, too.

Speaking as a former analyst, it seems highly unlikely to me that the vague language in the final IPO amendment would prompt all three underwriter analysts to immediately cut estimates without some sort of nod and wink from someone who knew how Facebook's second quarter was progressing. (To get this message from the language, you really have to read between the lines). But even if this is what happened, it is still unfair that news of the estimate cut wasn't disseminated quickly and clearly to everyone considering buying Facebook's IPO.

The bottom line is that, even if dissemination laws were followed to the letter (which frankly seems unlikely), the selective disclosure here was grossly unfair.

The SEC needs to look into this.

And as it does, the SEC should also revisit the practice that allows underwriter analysts to develop estimates that are used to market IPOs to institutional clients but are not shared with the public. In Europe, research analysts publish full reports on companies BEFORE they go public. This is a much better system, and the U.S. should switch to it. But at the very least, the SEC should mandate that any information given to some clients (e.g., earnings estimates and changes in earnings estimates) be given to all clients.